Sing (one's) heart out phrase
Sing can also be replaced with work, play, etc to express that you do something with great enthusiasm.
Sing in an extremely enthusiastic way.
All spectators rose to their feet and gave a big round of applause to the girl who had been singing her heart out.
When I have a chance to sing on a big stage, I will sing my heart out.
The verb" sing" must be conjugated according to its tense.
The origin of this phrase is not clear.
1. A pill or tablet that is hard for someone to swallow because of its large size
2. An fact, claim, proposal, etc. that is very difficult to believe or accept
1. The vet gave my adorable puppy a horse pill and he spat it out immediately.